Team discovers way to help heart failurepatients17 May 2017

Image of mouse heart and lungs, with arrows indicatingobstruction points that cause heart failure anddiaphragm weakening. Credit: A.J. Foster et al., ScienceTranslational Medicine (2017)

Shortness of breath is the No.1 complaint ofpeople suffering from heart failure. Now aUniversity of Guelph researcher has discovered itssurprising cause - and an effective treatment - in agroundbreaking new study.

Jeremy Simpson, a professor in U of G'sDepartment of Human Health and NutritionalSciences and the study's lead author, linkedshortness of breath in heart failure to a hormonalimbalance in the brain using mice.

The first-ever findings appear today in Science

Translational Medicine.

"We may not think of the brain as being the reasonwhy heart failure patients have trouble breathingwhen they walk up the stairs, especially when theheart is the sick organ," said Simpson, who workedon the study with Dalhousie University professorKeith Brunt. "But our organs talk to each other andthe brain talks to our diaphragm."

Known as dyspnea, shortness of breath affectspeople suffering from heart failure.

"For these patients, losing the ability to do dailytasks because of shortness-of-breath, is one of thehardest challenges of the disease," said Simpson.

However, treatment is typically focused on theheart and blood vessels and not the respiratorysystem, he added.

"We have known for decades that heart patientshave shortness of breath but we never really knewwhy," said Simpson. "It was generally believed thatfluid build-up in the lungs made it hard for heartpatients to breathe and assumed it was a side-effect of heart disease that couldn't be directlytreated."

But the researchers found using existing hormone-suppressing drugs that can reach the part of thebrain responsible for respiratory control to beeffective.

"If we can help these patients breathe easier wecan significantly improve their quality of life," saidSimpson.

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Images of mouse diaphragms showing evidence ofprogressive deterioration after several weeks of heartfailure (TAC). Credit: A.J. Foster et al., ScienceTranslational Medicine (2017)

Initially, the study involved following mice modelswith heart failure through a four-month progressionof the disease. Then the researchers made aninteresting discovery.

"Unlike previous research that examined the organsat the end stages of the disease, we were lookingat the changes happening as heart failuredevelops," said Simpson.

"We found the diaphragm, which is the mainmuscle we use to breathe, was being overworked."

The next step was determining why.

It's already known that people with heart failurehave increased levels of the hormonesnorepinephrine and angiotensin. The imbalancecauses high blood pressure and heart failure.

The researchers discovered these same twohormones are behind the diaphragm becomingweak.

"Essentially these hormones get into the brain andsend signals that push the diaphragm intounrelenting overdrive," said Simpson. "Bysuppressing these hormones, we can prevent thediaphragm from becoming weak."

Simpson said beta-blockers and angiotensin-receptor-blockers that can pass through the blood-brain barrier were successful at treating both theheart condition and diaphragm weakness.

"We don't need to wait for a new drug, which couldtake years or even decades to develop. We onlyhave to select the right drugs for the right patientsat the right time."

The findings may not only improve quality of life forheart patients, but also for patients with otherdiseases where shortness of breath is a symptom,Simpson said.

"Our goal in medicine isn't just to keep people alive,but to help them have the best quality of life

More information: A.J. Foster el al., "Central-acting therapeutics alleviate respiratory weaknesscaused by heart failure–induced ventilatoryoverdrive," Science Translational Medicine (2017). stm.sciencemag.org/lookup/doi/ …scitranslmed.aal4069

Provided by University of Guelph

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APA citation: Team discovers way to help heart failure patients (2017, May 17) retrieved 18 January2022 from https://medicalxpress.com/news/2017-05-team-heart-failure-patients.html

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